Verify Preorder Serialization of a Binary Tree

reference:
https://leetcode.com/discuss/83824/7-lines-easy-java-solution
https://leetcode.com/discuss/105664/clear-c-solution

c++

class Solution {
public:
    bool isValidSerialization(string preorder) {
        int degree = 1;
        string x;
        stringstream ss(preorder);
        while (getline(ss, x, ',')) {
            degree--;
            if (degree < 0) return false;
            if (x != "#") degree += 2;
        }
        return degree == 0;
    }
};

python

class Solution(object):
    def isValidSerialization(self, preorder):
        """
        :type preorder: str
        :rtype: bool
        """
        s = preorder.split(',')
        degree = 1
        for x in s:
            degree -= 1 # in degree 
            if degree<0:return False
            if x != '#': degree += 2 # out degree 
        return degree == 0